With 20+ years of NIH-R01 grant support the Frey and Sgouros labs have developed quantitative imaging and patented dosimetry methods that enable treatment planning of combination external beam radiotherapy (XRT) and radiopharmaceutical therapy (RPT). Combination XRT-RPT is orthogonal in terms of toxicity. RPT is especially suitable for disseminated cancer while providing a dose boost to tumors targeted by XRT. The overall workflow is to reconstruct and quantify the SPECT/CT images from RPT planning study, calculate dose-rate maps at each time point, integrate the dose-rate maps to create a dose map, using radiobiological principles convert the dose map to be consistent with XRT doses and combine this with a Sim-CT for import into an XRT dose planning system. The current implementation involves several discrete software packages and manual conversion steps and is tedious, error prone, and not suitable for clinical implementation or commercialization. The overall objective of this Phase I application is create a single streamlined, robust, integrated, and validated software package for combining RPT and XRT. We will: (1) Create develop the integrated software; (2) validate it using existing clinical data; and (3) prepare to submit an FDA IDE in preparation for the proposed trial in Phase II.